Method of fusing lamp-filaments to leading-in wires.



J. W. HOWELL. METHOD OF FUSING LAMP FILAMENTS TO LEADING-IN WIRES.APPLICATION rlLzp'un. 16, 1907.

1,022,553, I Patented Apr. 9, 1912.

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Whinesses:

UNITED STATES T OFFICE.

JOHN W; HOWELL. 0F NEWARK, NEW JERSEY. ASSIGNOR TO GENERAL ELECTRICCOMPANY. A CORPORATION OF NEW YORK.

METHOD OF FUSING LAMP-FILAMENTS TO LEADING-IN WIRES.

To all whom it may concern:

Be it known that I, Jonx llownnn. a citizen of the United States,residing at Newark, county of Essex. State of New Jen sey, have inventedcertain new and useful Improvements in Methods of Fusing Lamp-Fila-ments toLeading-ln ires, of which the following is a Specification.

Incandescent lamp filaments consisting of a refractory metal, such astungsten. molybdenum, boron, titanium. etc., may he advantageouslysupplied with current through a leading-1n conductor fused or welded tothc filament. Such a joint affords a rigid connectionof goodconductivityand free from any carbonaceous or other vaporizablc materialwhich might. contaminate the filament. Such awelded connection can bemade to a platinum leading-in w'iro by means of an electric arc in anon-oxidizing atmosphere. The platinum leading-in wire fuses into aglobule and appears to alloy or otherwise combine with the tungsten ofthe filament.

. According to my present invention the filament is connected by awelding or fusing operation with a leading-in conductor or wireconsisting of a metal or material which does not readily alloy orcombine with the material of the filament. When the two materials are ofthis nature, there is no danger that the fused globule will soak intothe filament and possibly change its refractory qualities in immediateproximity to the Welded joint. According to the process hereinafterdescribed, a large proportion of perfect joints are obtainable and thewelding or fusing operation is performed in such a manner that thefilaments are protected from the deteriorating action of the weldingarc.

According to my invention, the leading-in conductor or supporting wireto which the filament is to be connected is provided with a thin tubularportion bent downward 'to form a socket for the reception of the end ofthe filament. The fusing arc is drawn from the lower end of the tubularsocket and therefore at some distance from the filament. or morestrictly speaking. atsome distance from the portion of the filamentoperating at incandescence when the lamp is m use.

The details of my invention will be better Specification of LettersPatent.

Application filed March 16. 1907.

Serial No. 362,610.

understood by reference to the accompanying drawing. in which- Figure lis a sectional elevation of an apparatus suitable for carrying out thewelding operation: Fig. 2 is an enlarged view of the joint before thearc is formed; and Fig. 3 is an enlarged view of the finishedconnection.

The welding operation may be carried out in a glass envelop 1 providedat the top with-an inlet 3 through which hydrogen or other non-oxidizinggas may he continuously supplied. The envelop may be open at the bottomfor the convenient introduction of a lamp stem 3 carrying a about whichthe several metal filaments 5 are grouped. These filaments may consistof pure tungsten or of other refractory metals and materials. Leading-inconductors or support wires 6 of copper or other suitable metal. may bearranged axially about the pedestal 4. as shown in the drawing- Beforeassembling the lamp, each leading-in wire is flattened at the end andthen drawn through a die to shape the fiattened port-ion into a tube 7,as illustrated in Fig. 2. This tube is bent downward at a substantiallyright angle to the leading-in conductor and thus scrves'as a convenientfsockot for the end of a lamp filament 5.

The order of procedure is as follows: The leading-in conductor is placedin the notched end of a rod 8 which projects through an opening in thewall of the glass envelop 1. and is connected to a source of energy 9.This rod serves to conduct the arc-producing current. An electrode 10 ofcarbon. metal. or other suitable material is connected with the otherterminal ofthe source and is movable through an opening 'll in the wallof the envelop. To produce the weld. the carbon electrode is brought incontact with the lower end of the tubular socket T and is then quick];withdrawn to produce a heating arc. The lower end of the tube quicklyfuses up and gathers in a ,g'lo-bule about the metal filament and thensolidifies. The upper end of the tube is preferably left unfused, for itthen acts as an anchor for the filament during the welding operation.and so keeps the filament een-.

trallv located in the fused part. Unless the filament. is thus anchored.it may more entirely out of theglobule. Owing to the Patented Apr. 9,1912.

distance between the carbon electrode and the filament, the latter isnot subjected to the deteriorating action of the arc.

It is of great importance to select for the leading-in wire, a materialwhich does not alloy or combine with the material of the filament,as forinstance, copper wire for tungsten filaments. No flux is used and thefused portion of the copper conductor remains unalloyed.

\Vhat I claim as new, and desire to secure I by Letters Patent of theUnited States, is,

1. The process which consists in rigidly securing a tungsten lampfilament to a copper support and then fusing a portion of said supportto form a connection of good conductivity, leaving unfused a portion ofsaid support to which said filament is secured, said unfused portion ofsaid support being adjacent the operative part of said filament.

2. In an incandescent lamp, the combination of a tungsten filament, anda copper leading-in wire having a portion fused about said filament andan unfused portion supporting the filament.

3. The method which consists in fusing a port-ion of a metallic memberabout a refractory filament of material which does not readily combinewith that of said memher, to form a conductive joint while the filamentis maintained by another portion v of said member in a position where itwill be inclosed in the fused metal.

4. The method which consists infusing the end of a copper member about atungsten filament to form a conductive joint while the filament ismaintained in proper relation to the fused end of the member by anotherportion thereof.

5. The combination with a refractory filament of a current conductor ofmaterial inert with respect to that of the filament loosely embracingone portion thereof and fused about a portion of the filament fartherfrom the principal luminous portion than the portion thus embraced.

' 6. In an incandescent lamp the combination of a tungsten filament anda support wire therefor having a bent portion surrounding a part of thefilament next to the operating portion thereof and fused about thefilament at a point away from the operating portion of the filament.

In witness whereof, I have hereunto set my hand this 8th day of March,1907.

JOHN \V. I-IOVELL. W'itnesses:

J. HARRY Euuxs, S. N. \VHITEHEAD.

